1. Field of the Invention
The invention is in the field of energy storage devices, including but not limited to batteries, capacitors and fuel cells.
2. Related Art
Rechargeable lithium ion batteries are key electrical energy storage devices for power supply in portable electronics, power tools, and future electric vehicles. Improving the specific energy capacity, charging/discharging speed, and cycling lifetime is critical for their broader applications.
In current commercial Li-ion batteries, graphite or other carbonaceous materials are used as the anodes which have a theoretical capacity limit at 372 mAh/g by forming fully intercalated LiC6 compound. In contrast, silicon has a much higher theoretical specific capacity of 4,200 mAh/g by forming fully lithiated alloy Li4.4Si. However, the large volume expansion of lithiated Si by up to ˜300% causes great structural stress that in the past inevitably lead to fractures and mechanical failure, which significantly limited the lifetime of Si anodes.